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Motion Detectors with Infrared Sensors

2014-11-21 09:26  
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Motion detectors often we hear, is to use ultrasonic sensors, the advantages of this sensor is sensitive and rapid response. But the main problem is that sometimes these sensors also respond to vibration in the environment, such as a passing car or plane sound, which resulted in an error response that we did not expect. This can be overcome by using active infrared sensors. The basic concept is similar to an ultrasonic sensor as shown below:

Blog diagram Motion Detectors with Infrared Sensors1 Motion Detectors with Infrared Sensors

As transmitter Photodioda out pulses of infrared light with a certain frequency 5KHz, then reflected by the reflector in front of him. and received by the phototransistor as the receiver. The detected object is located in between the transmitter-receiver with a reflector. The following is a schematic drawing:

Motion Detectors with Infrared Sensors1 Motion Detectors with Infrared Sensors

Circuit on the left is the transmitter circuit that produces an infrared pulse modulation 5KHz. On the right side (receiver circuit) there is “resonance tuned amplifier” that we can control bandwidth in order to capture the pulse modulation transmitter 5Khz. Bandwidth control also serves to reduce the sensitivity to the effects of light around him.

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